3d cursor on position of vertex of subdivision modifier mesh with 'adjust cage' on
One way would be to duplicate the object in Object Mode and then, for the duplicate only, apply the Subdivision Surface modifier. Then, snap the 3D Cursor to the desired vertex on this new version of the mesh. Afterwards, either hide the new version of this mesh, or, put it in a new collection so that it can be referenced at will in the future for this same purpose. You could also delete it if you know you don't need it anymore. But you now have your desired 3D Cursor position, and you still have your original mesh with a Subdivision Surface modifier that remains unapplied.